Limiting strain relaxation in iii-nitride hetero-structures by substrate and epitaxial layer patterning

Abstract

A method of fabricating a substrate for a semipolar III-nitride device, comprising patterning and forming one or more mesas on a surface of a semipolar III-nitride substrate or epilayer, thereby forming a patterned surface of the semipolar III-nitride substrate or epilayer including each of the mesas with a dimension / along a direction of a threading dislocation glide, wherein the threading dislocation glide results from a III-nitride layer deposited heteroepitaxially and coherently on a non-patterned surface of the substrate or epilayer.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit under 35 U.S.C. Section 119(e) of co-pending and commonly-assigned U.S. Provisional Application Ser. No. 61 / 406,876 filed on Oct. 26, 2010, by James S. Speck, Anurag Tyagi, Steven P. DenBaars, and Shuji Nakamura, entitled “LIMITING STRAIN RELAXATION IN III-NITRIDE HETEROSTRUCTURES BY SUBSTRATE AND EPITAXIAL LAYER PATTERNING,” attorney's docket number 30794.387-US-P1 (2010-804), which application is incorporated by reference herein.[0002]This application is related to co-pending and commonly assigned U.S. Utility patent application Ser. No. ______, filed on same date herewith, by James S. Speck, Anurag Tyagi, Alexey Romanov, Shuji Nakamura, and Steven P. DenBaars, entitled “VICINAL SEMIPOLAR III-NITRIDE SUBSTRATES TO COMPENSATE TILT FO RELAXED HETERO-EPITAXIAL LAYERS,” attorney' docket number 30794.386-US-U1 (2010-973), which application claims the benefit under 35 U.S.C. Section 119(e) of co-pending and...

AI Technical Summary

Benefits of technology

The present invention provides a method to limit strain relaxation of hetero-epitaxial III-nitride layers grown on a III-nitride substrate / epilayers by patterning the substrate / epilayer. This is achieved by growing the layers on a patterned surface of the substrate / epilayer, where the patterned surface has a threading dislocation density of 106 cm−2 or more. The resulting device has a misfit dislocation density of 104 cm−2 or less. The invention also includes growth and fabrication of devices on patterned III-nitride substrates and hetero-interfaces with reduced misfit dislocation density. The device can be a light emitting diode or laser diode, and the active layers can include quantum wells. The invention also provides a method of fabricating a substrate for a semipolar or non-polar III-nitride device by patterning and forming mesas on a surface of a semipolar or non-polar III-nitride substrate or epilayer, where each mesa has a dimension / along a direction of a threading dislocation glide.

Problems solved by technology

In spite of numerous advantages offered by growth of optoelectronic devices on nonpolar / semipolar III-nitride substrates, misfit dislocation (MD) formation at misfitting heterointerfaces [1, 2] can make it difficult for device manufacturers to fully realize the expected inherent advantages.

This can, in turn, limit the device design space e.g. the range of emission wavelength for Light Emitting Diodes (LEDs) / Laser Diodes (LDs).

Additionally, performance for LDs can be affected due to poor optical waveguiding provided by thinner / lower composition waveguiding (typically InGaN) and cladding layers (typically AlGaN).

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